The memory of a computer is frequently divided into pages or page frames. When a program is to be run, it is assigned a certain number of available pages of memory. As the program runs, it makes reference to memory for information, data or subroutines. Some programs or special sections of code, commonly referred to as "subroutines," in a program require that all information, data and subroutines, hereinafter memory references, to be requested be in assigned available memory in order for the special section of code to operate. In the event the special section of code makes such a memory reference, and the reference is not available in the assigned memory, the program undergoes a page fault and an error occurs. In order to avoid this error condition, it is common practice to do a preliminary check to make sure that all required memory references are available to the program before it is run. All of the memory references are then marked or wired into assigned memory so they cannot be erased or moved out of memory before the special section of code is run. The running of this check program requires an extended period of time, much of which is wasted since more often than not all of the requested memory references are available. More time is lost after the program is run in going back through the memory unmarking or unwiring all of the memory references.
It is therefore an object of the present invention to be able to operate a program or special section of code which requires the presence of all memory references in order to avoid a page fault without the time loss involved in running a check program beforehand.
It is also an object of the present invention to provide a data processing system and method of operation which assumes that all memory references to be requested are present, since more often than not they are, and which provides a procedure for taking care of those few instances when the memory reference is not available.